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This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 07-12-2011, 03:47 PM   #1
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Join Date: Aug 2010
Location: Reston, VA
Posts: 2,674
My Ride: 77' 924 87' E30
Exclamation Still Suffering from hesitation/bucking even after VANOS seals? Look Inside!

My car has suffered from a slight hesitation when taking off and under load, and also when suddenly accelerating under load at low rpm's up until 3k in 1st through 2nd even well after 3k miles on the beisansystems.com seals.

So I went in and looked at the MAF, cleaned it and also inside the connector I crimped down the pins inside so it would grab the receiving end pins better--that helped but the hesitation was still there.

Just 3 days ago I decided to clean and evenly crimped (using a pick) down the pins inside the connector for the exhaust VANOS solenoid; I took it for a spin and lo and behold the hesitation was pretty much gone! A few days went by and the more I drove the car the more low end torque it developed and it revved up smoother and smoother.

Yesterday, I did the same thing to the intake VANOS solenoid connector. Took it for a spin and the car felt as if the DME was relearning it's VANOS adaptations all over again! (felt sluggish at the beginning and started feeling stronger about 3 to 6 minutes later) 30 miles later the car feels great! and there is absolutely no hesitation under any circumstances!

The hesitation was caused due to shoddy and loose contact between the solenoid and it's receiving end [VANOS solenoid contacts]-- In other words

Originally Posted by Optio View Post
I believe that the issue is this..........

The contact width are set to the high side of the spec. The signal that is traveling across these contacts is quite weak. In other words, the current draw is very small. The device of interest, is not receiving the full signal strength from the PCM. Hence the sluggish performance of the VANOS. The best analogy that I can think of: Measuring the resistance of a conductor with a DMM. You will obtain one value when gently touching the conductor with the leads and a different reading when you press hard.
The pins inside both pigtails were spread open for some reason unknown to me.

The new found torque and instantaneous throttle response caught me off guard yesterday during a on and off drizzle when I punched it at 2750rpm in 2nd gear-- The rear end of the car kicked out to the side as if it had an LSD! (yes, I always drive with traction control off--at least when I can remember to turn it off.)

This is my MAF connector but the same concept applies to the VANOS connectors since they are the same in design.

You basically wedge a pick at the top and bottom of the filaments inside closing them together. Not all the way obviously but enough so that when it is plugged in it will open slighly and grab/bite the pins on the receiving end.

I've already done it to the image above. I don't have a before picture but the filaments were spread open and did not form a perfect rectangle as they do now.

Now after you have done so; Now when you are about to connect the pigtail you can feel some resistance ( which indicates the pins have a much better contact with the solenoid pins ) whereas before they simply just slid in like butter; Almost as if they were sliding into a void.

This trick would also work for MAF, DISA, IAT, Alternator pigtails, and all pigtails with the same design throughout the car.

Here's what Rajaie--Owner of besiansystems.com--had to say.

Originally Posted by Rajaie View Post
Congrats on the find and repair!
Thanks for sharing this important info!

I have not heard of this before. It seems reasonable it could be a problem.
There have been owners that complained of a hesitation that the vanos seals didn't resolve.

Some owners replace the vanos seals and receive little or no benefit. I know if they have another performance related problem they won't receive the benefits of the new seals until the problem is resolved. But in some cases it seems they have no performance problem. I've always wondered in these cases what is going on. Maybe what you found is a relevant cause.
Spray cleaning connectors with electrical contact cleaner is a good idea. But I had not considered crimping the pins.

Did your pins seem excessively open?
Which reminds me I need to detail my engine bay...

Lets try to keep this thread strictly on the topic at hand

For those who don't bother with searching [and newbs]...

For a in-depth VANOS walk-through


To purchase


E46 besiansystems.com support thread

Bilstein HD's | E30 M3 FCAB's | H&R OE Sports | F+R strut bars | Self tuned 027 93 octane chip | KoseiK1's on R888's | + crazy OCD maintenance

Last edited by Solidjake; 12-20-2014 at 08:20 AM.
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